1. Field of the Invention
The invention relates to the fields of physics and materials science, and relates to a magneto-electronic component as it can be used, for example, as a digital memory, and to a method for the production thereof.
2. Discussion of Background Information
Magnetic shift registers, also referred to as “racetrack memory devices,” are magnetic memories that combine the sturdiness of flash memories, the speed of DRAM memories and the reversibility and non-liquidity of hard drives with one another. Racetrack memories of this type have been scientifically studied by and are known from S. S. P. Parkin, M. Hayashi, L. Thomas, “Magnetic Domain-Wall Racetrack Memory,” Science 320, 190-194 (2008). Elongate ferromagnetic memory structures are divided into magnetic domains with differing orientation of the magnetic moment. These magnetic domains are separated by domain walls, which can be moved in the data medium. An effect is thereby utilized which is known as the spin transfer torque effect, and results in magnetic domain walls being able to be moved in thin memory structures in a controlled manner along these memory structures by the application of electric currents. Digital data are coded into the interval between two consecutive domain walls. Racetrack memories of this type can be constructed in a two-dimensional alignment—horizontal nanowires on a substrate—or in a three-dimensional alignment—U-shaped, vertical nanowires that are connected to a substrate and/or to electrodes in the lower U-region—(S. S. P. Parkin et al., Science 320, 190-194 (2008)).
A basic requirement for the functioning of racetrack memories is the quick and controlled movement of domain walls along thin magnetic strips. Here, it is particularly important that the rate of the movement of the domain walls is as high as possible. For this purpose, a magneto-electronic component is known according to DE 10 2009 021 400 A1 which consists of an elongate ferromagnetic material, along which magnetic domain walls move, wherein the transversal magnetization direction of the domain walls at their center has no direction of preference on the plane perpendicular to their direction of movement along the elongate ferromagnetic material.
Likewise, known are magnetic racetrack memories that consist of an elongate magnetic material, a current source, a writing device and reading device, and a write-back loop, wherein the elongate magnetic material has a plurality of magnetic domains (KR 10 2009 0127705 A).
Furthermore, an elongate material is known from US 2010/0085793 A1 in which at least two regions with a plurality of magnetic domains are present, which regions are separated from one another by a non-magnetic material and which prevent a movement of the domain walls from one region to the other. When an electric current is applied, the regions in which data are stored move in a direction of the current flow.
From U.S. Pat. No. 7,551,469 B1, a unidirectional racetrack memory is known. In this memory, the domain walls move in only one direction along the direction of current flow. The writing element can hereby be arranged at one end of the elongate memory and the reading element at the other end.
Disadvantageous in the case of the known solutions for racetrack memories is the practical implementation, in particular for three-dimensional solutions. The arrangement of individual horizontal nanowires on a substrate is technically achievable. However, precisely the special advantage of such a memory, the high storage density, cannot be achieved by such an arrangement. The arrangement suggested by the prior art for three-dimensional solutions for racetrack memories in the form of U-shaped nanowires, which in the lower region of the U are provided with electric contacts and are possibly arranged on a substrate, is also already not technically feasible because the plurality of such U-shaped nanowires must not come into contact with one another, and furthermore, because each nanowire must be individually connected to an electric current source. Accordingly, there are currently no other suggestions for three-dimensional racetrack memories aside from this suggestion by S. S. P. Parkin, and above all, no technical solution.